Loch Gairloch and Loch Ewe lie on the north-west Scottish mainland in an area of Torridonian sandstone. They were surveyed during 1990 as part of the survey of Scottish sealochs. Although adjacent, the two lochs are very different in character. Loch Ewe is a north-facing fiord with two main sills and basins, a maximum depth of 73 m and is mostly sheltered from wave action. Loch Gairloch faces west, has no sills and is exposed over much of its length. It has depths of over 100 m at its entrance and appears to have more open coast affinities than Loch Ewe with warmer, clearer water. Tidal streams are negligible in both lochs. The lochs have extensive sandy beaches and hold a wide range of sublittoral sediments which, although predominantly coarse, grade to soft mud. Hard substrata were common in shallow water in both lochs but limited in deeper water. The lochs are situated in a popular holiday area with the Inverewe gardens one of the major attractions. There is a large caravan site on Loch Gairloch and numerous holiday apartments. There are small sewage outfalls around both lochs, a NATO refuelling jetty in Loch Ewe and a fishing harbour in Loch Gairloch. Both lochs have mussel farms and Loch Ewe also has salmon cages. There are two SSSI's in the areas, one of which borders the head of Loch Gairloch. There has been a great deal of marine research carried out in the area, and particularly Loch Ewe, on account of the SOAFD (formerly DAFS) laboratory at Firemore Bay. Of note was a Phase 1 diving survey carried out in 1989 by a Seasearch team (Gubbay 1990). Ninety-seven sites were surveyed which included 69 diving sites, 13 dregde samples, 10 suction samples and 11 littoral surveys; 32 habitat/community types are described. Both lochs could be divided into inner, central and outer zones with cape Laminaria saccharina forest in the inner, mixed kelp forest in the cental and Laminaria hyperborea forest in the outer zone. Although some sites were grazed by sea urchins, at many there was a luxuriant understorey flora often dominated by filamentous brown algae. Circalittoral bedrock and boulders were more limited in extent. In the outer lochs, these held ascidians and hydroids to a depth of 24 m. The brachiopod Neocrania anomala was found on deeper and more sheltered boulders. Deep, sheltered bedrock with the anemone Protanthea simplex was only found at Resolution Rock in Loch Ewe. The sediments were predominatly sandy and were often very rich, particularly in Loch Gairloch. Waves of coarse, shelly gravel with maerl were found in the outer parts of both lochs. In slightly more sheltered water, there were large expanses of firm, fine sand with species such as the echinoderms Echinocardium cordatum and Labidoplax digitata. In deeper water this merged into sandy mud with seapens. With increasing shelter, the sediments became muddier and more stable, supporting dense algal populations in shallow water. In Loch Shieldaig, the most sheltered basin, very soft mud was covered with a filamentous algal blanket. Soft mud in deeper water held burrowing crustacens such as the prawn Nephrops norvegicus. There was a small bed of eel grass Zostera marina at the entrance to Loch Gairloch and maerl with the flame shell Limaria hians was found at the head of Loch Ewe. Littoral communities were less varied with the majority of shores consisting of moderately exposed bedrock and boulders and numerous fine sandy beaches. Sheltered shores dominated by Ascophyllum nodosum were restricted to the heads of lochs, where the free-living growth form A. nodosum f. mackaii was also found. Nine habitat/community types and 22 species have been provisionally assessed to be of Loch or Regional nature conservation importance. Records currently considered sensitive have been removed from this dataset.